Electronic shelf labels (ESLs) are seeing widespread use, as they can potentially save retailers resources by being updatable from a central location over a network, rather than manually as previous solutions required. They can also enable new features like on line advertising and frequent price changes based on time, day, shop activities, discount periods, and more.
FIG. 1 is a block diagram of a conventional ESL 100. The ESL 100 includes a controller 110 coupled to a receiver 120, a memory 130, and a display 140. The receiver 120 is connected to an antenna (not shown) to receive data. The information displayed on the display 140 can be updated dynamically during use of the ESL 100, for example, in response to receipt of data from a server (not shown). The displayed information may be in a format of text data, graphics, or both. The displayed information may include a SKU, product description, current price, promotion, and the like.
The ESL 100 also includes a power supply 150 to power the various electronic circuitries in the ESL. In a typical implementation, the power supply 150 is a battery or a capacitor. The battery or capacitor may be rechargeable using a solar power source 155 coupled to the power supply 150.
Typically, ESLs are low power devices and their power supplies or sources impose some limitations on their usage. For example, when an ESL is powered by a battery, the battery must be frequently replaced upon depletion. However, discarding such batteries is not always simple, as batteries have to be disposed of properly, and in many cases in accordance with regulations. Taxes and penalties are regularly associated with the disposal of hazardous materials such as batteries.
Using rechargeable power supplies does not properly solve the limitations of frequent replacement of ESL. Currently available rechargeable ESLs suffer from low number of charge/discharge cycles. That is, after a few numbers of charge/discharge cycles of the power supply, such a power supply becomes depleted. Further, in current implementations, the charging time of a power supply is relatively long, which causes ESL to malfunction during the charging time.
In addition, rechargeable ESLs are not designed to include circuitries to regulate the current for charging the power supply. ESLs are typically installed indoors (e.g., in supermarkets). The output of the solar power source can vary considerably with changes in environmental conditions, such as radiance from light sources and temperature of the operating environment. Given the dynamic changes, an output current of the solar power source can fluctuate and, thus, the solar power source does not provide the optimal efficiency for charging the power supply. Moreover, an overcharge current may harm the power supply.
It is therefore desirable to provide an ESL with an improved life cycle over prior art solutions.